1. Field of the Invention
The present invention relates to a process for transforming a polymer base into a polymer based finished article comprising individualized elements and presenting a shaded appearance of anisotropic coloring. xe2x80x9cIndividualized elementsxe2x80x9d should be read as meaning pieces or basic constituent elements forming distinct entities the minimum size of which is sufficient for observation of coloring anisotropy. The xe2x80x9cshaded appearance of anisotropic coloringxe2x80x9d should be read as meaning random variation of coloring existing in all directions from any point in the body of the individualized elements. The present invention also relates to a polymer based finished article comprising individualized elements having such a shaded appearance of anisotropic-coloring. Such a polymer based finished article comprising individualized elements can be obtained, in particular, through the use of the process according to the invention.
2. Prior Art
Various processes are known, according to the prior art, for producing polymer based manufactured products, for example polymer surface coatings. The specific final form desired for such products is obtained using an apparatus supplying, for instance, slabs of varying size and thickness or widths, which are then applied as they are by gluing or any other means to the support to be coated. Such products can also be used, after cutting to the desired shape and size, as patterns in floor coatings cast in situ, these patterns being arranged in a predetermined fashion and inserted without joints into a flexible resin, such as that described by the Applicant in patent EP 0 743 405.
Various methods are also known for producing cast surface coatings based on polymer granules incorporated in a resin type binder. One can thus obtain a cast surface coating that is essentially inalterable under usual conditions of wear, and the visual appearance of which is of the mosaic, single color or multicolored type.
By way of example can be mentioned patent FR 2 541 296 which describes such cast coatings based on rubber granules, which may be colored, and which are spread in practically random fashion and inserted into a binder. The processes for manufacturing such products intended, for example, for the manufacture of surface coatings, include steps of mixing a base polymer with additives, of extrusion, of calendering or some other shaping, of vulcanization and then of cooling the mixture, as applicable, and final shaping, for example as panels, slabs or widths by shape conferring equipments. Furthermore, such products are usually colored by adding colorants at the time they are manufactured. The aim is to obtain products of a homogeneous color. Multi-colored surface coatings are, indeed, obtained by mixing several colors, or shades of color, of polymer products obtained during successive manufacturing operations. Thus, all the polymer products of each type, or batch, are identical, with an isotropic coloring, that is to say homogeneous in the body of the product. The coatings obtained with these products have the drawback of having an artificial visual appearance, because they are uniform, in comparison with hard natural materials such as, for example, marble or stones or the like, whether crushed or not.
To overcome this drawback, arrangements are made to manufacture in works surface coatings produced with these products but having shades of coloring. Such shades of coloring can be obtained by dispersion of an added layer of colorant on the surface or by encrusting colored materials, which makes it impossible to carry out sanding or buffing to renovate the appearance thereof. Moreover, the visual appearance obtained with these processes fails to cause the artificial appearance to disappear completely.
U.S. Pat. No. 2,495,241 discloses that, in mixtures of polymers, intended for the manufacture of asphalt tiles, a contrasting colorant is incorporated so that the operation of mixing this colorant with the mixture of polymers leads to irregular distribution of the colorant in the mixture, this operation is terminated before the colorant has become uniformly mixed.
U.S. Pat. No. 3,570,056 discloses a process for manufacturing polymer products simulating marble and a device permitting the manufacture of articles of a rectangular shape in the form of large sheets comprising veins of colorant imparting thereto non-homogeneous coloring. U.S. Pat. No. 3,529,325 discloses a device the configuration of which permits the implementation of a process for the manufacture of polymer based products usable as building materials, in the form, for example, of strips in the bodies of which there are three-dimensional veined patterns of coloring.
These manufactured products, which are modular finished products, represent an improvement, but there remains a need, in this field, to obtain polymer based articles having very irregularly distributed surface coloring, yielding a non-artificial appearance by comparison with materials formed of slabs of natural marble or fragments of natural marble and/or crushed marble or the like and that is resistant to wear.
The present invention aims to achieve this result, by means of a simple, inexpensive process.
The invention relates to a process for transforming a polymer base, having a shaded appearance of anisotropic coloring, into a finished article, the process including operations of mixing a base polymer and additives, of adding a shading colorant to the polymer mixture, followed by incomplete homogenization of the shading colorant in the polymer mixture to form the polymer base with a shaded appearance of anisotropic coloring, subsequent shaping to an intermediate predetermined shape, and vulcanization and cooling as applicable, and then an operation of breaking up the shaded polymer base into individualized elements and an operation of aggregation of said elements in any desired arrangement to obtain the finished article. It also relates to a finished article, having such anisotropy, constituted by an agglomerate of individualized elements, and its application as a surface coating.